The First Avenue South Bridge will be closed on Monday for three days for repairs. It's the first part of a three part repair process. The north bound lanes are set to be replaced in 2027.
Photo courtesy of Washington State Department of Transportation
UPDATE March 11
After beginning repairs on the First Avenue South bridge WSDOT now expects the closure to remain in place through 11:59 p.m. on Friday, March 13.
According to the agency, bridge maintenance crews have been working since the full closure began on Monday morning, March 9, modifying existing grated panels and installing steel plates over the cracked sections to safely reopen all lanes.
Inspectors later discovered the damage was more extensive than initially believed, and WSDOT says the process of realigning the bridge spans requires highly precise work.
The repairs underway this week are intended to stabilize the structure ahead of a second phase of work scheduled for mid‑to‑late April.
UPDATE March 9
From 5 a.m. Monday, March 9, through 8 p.m. Wednesday, March 11, all northbound lanes of the SR 99 First Ave S Bridge in Seattle will close so crews can make urgent temporary repairs.
A recent bridge inspection found cracks in some of the steel deck grates. During the closure, crews will modify the grated panels and install steel plates over the cracked sections to reinforce the bridge and restore safe vehicle access across all lanes. These repairs are temporary but necessary while a long-term replacement plan is developed.
Marine traffic under the bridge will continue as normal, but drivers will need to use alternate routes like I-5 or I-405.
This closure comes at a time when NB I-5 is already reduced to two lanes across the Ship Canal Bridge, so drivers should expect heavy traffic and longer commutes across the region early next week while SR 99 is closed.
The repair window also falls between two major I-405 closures in Bothell (March 7–8 and March 13–16), allowing crews to address the bridge repairs as quickly as possible.
Original Post March 5
The northbound 1st Avenue South Bridge (SR 99) is facing a major, multi‑phase repair plan, and the first big closure is happening March 9–11, 2026. This is the result of cracks discovered in the steel deck grates during a February 18 inspection. Multiple outlets and WSDOT itself have now confirmed the timeline and scope.
What’s happening now
WSDOT will close all northbound lanes of the 1st Ave S Bridge for three days:
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Starts: Monday, March 9, 2026 at 5 a.m.
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Ends: Wednesday, March 11, 2026 at 8 p.m.
This closure allows crews to install temporary steel plates to stabilize cracked deck grates. Two lanes have already been closed since Feb. 18 for safety.
Why the closure is necessary
Inspectors found cracks in the steel deck grates on the northbound drawspan.
The full repair plan (3 phases)
WSDOT has laid out a year‑long, three‑phase approach:
Phase 1 — March 9–11, 2026
Phase 2 — Mid to late April 2026
Phase 3 — 2027
What drivers should expect
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Heavy congestion on West Seattle Bridge, South Park Bridge, and 5th Ave S detours
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Reduced speeds (25 mph) even after reopening
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Additional closures in April and again in 2027
For West Seattle and South Park travelers
This is the same corridor you rely on for Harbor Ave, West Marginal, and the Duwamish crossings. The three‑day closure will push a lot of traffic onto the South Park Bridge and 1st Ave S ramps, so expect backups similar to the West Seattle Bridge closure era, but shorter.
